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<h2><span class="refentrytitle">Function template get_mpi_datatype</span></h2>
<p>boost::mpi::get_mpi_datatype — Returns an MPI data type for a C++ type. </p>
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<h2 class="refsynopsisdiv-title">Synopsis</h2>
<div class="refsynopsisdiv"><pre class="synopsis"><span class="comment">// In header: &lt;<a class="link" href="../../mpi/reference.html#header.boost.mpi.datatype_hpp" title="Header &lt;boost/mpi/datatype.hpp&gt;">boost/mpi/datatype.hpp</a>&gt;

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<span class="keyword">template</span><span class="special">&lt;</span><span class="keyword">typename</span> T<span class="special">&gt;</span> <span class="identifier">MPI_Datatype</span> <span class="identifier">get_mpi_datatype</span><span class="special">(</span><span class="keyword">const</span> <span class="identifier">T</span> <span class="special">&amp;</span> x<span class="special">)</span><span class="special">;</span></pre></div>
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<a name="id-1.3.25.7.9.12.4"></a><h2>Description</h2>
<p>The function creates an MPI data type for the given object <code class="computeroutput">x</code>. The first time it is called for a class <code class="computeroutput">T</code>, the MPI data type is created and cached. Subsequent calls for objects of the same type <code class="computeroutput">T</code> return the cached MPI data type. The type <code class="computeroutput">T</code> must allow creation of an MPI data type. That is, it must be Serializable and <code class="computeroutput">is_mpi_datatype&lt;T&gt;</code> must derive <code class="computeroutput">mpl::true_</code>.</p>
<p>For fundamental MPI types, a copy of the MPI data type of the MPI library is returned.</p>
<p>Note that since the data types are cached, the caller should never call <code class="computeroutput">MPI_Type_free()</code> for the MPI data type returned by this call.</p>
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<td><p><span class="term">Parameters:</span></p></td>
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<td><p><span class="term"><code class="computeroutput">x</code></span></p></td>
<td><p>for an optimized call, a constructed object of the type should be passed; otherwise, an object will be default-constructed.</p></td>
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<td><p><span class="term">Returns:</span></p></td>
<td><p>The MPI data type corresponding to type <code class="computeroutput">T</code>. </p></td>
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<div class="copyright-footer">Copyright © 2005-2007 Douglas Gregor,
      Matthias Troyer, Trustees of Indiana University<p>
        Distributed under the Boost Software License, Version 1.0. (See accompanying
        file LICENSE_1_0.txt or copy at &lt;ulink url="http://www.boost.org/LICENSE_1_0.txt"&gt;
        http://www.boost.org/LICENSE_1_0.txt &lt;/ulink&gt;)
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